Hi! So my current setup are Dual 6x9 200w rear deck and Dual 5.25 in the front doors. I’m wanting to know if it would be possible to mount 6x9 speakers in the rear doors and splice them to existing wires. Would this cause any issues with power to my speakers? Would doing this result in screwing up my head unit at all? I have an aftermarket Sony head unit, I don’t know the exact model. Thanks!